The simple answer is that what you are proposing is a lot of work and warranty-voiding for an impractically tiny range (and in the case of most std hybrids a mode of operation that the powertrain ecu wont do anyway).

I'm waiting to do a 5000 my update in my Volt thread, but here is an interim update on a vehicle that is designed to operate exactly as you propose in the OP.

The effects of my early 1000 mile trip are finally starting to diminish on my statistics, and our normal round town plus occasional 70-100 mile trips have let us hit the sweet point of plug-in hybridism..

over the last 30 days we have averaged 269 mpg, over the last 1000miles we are at 120 mpg and over the whole life so far (4485mi) we are up to 70 mpg.

I actually was asking why ALL hybrids don't have an AC charger for filling the battery at night, even though it might be of minor benefit to the normal hybrids.

You can imagine the cost of a "safe" plug-in charger, connector, EVSE system and components that are not needed for a std hybrid - which is already at a disadvantage price-wise.

And if you look at how the std hybrids operate, they still require engine operation for normal operation, so even if you topped up the battery for the couple miles, it would still kick on the engine for various reasons.

Toyota's plug in Prius at 10-12 miles range is already scrapping the bottom of the range limit that makes sense (for California HOV lane exemption mainly) - for the vehicles you are talking about, it would be <5 miles, not worth it at all assuming your could overcome the programming and moding problems as well.

Hey, in the OP,s first paragraph. The Chevrolet Volt is WHAT YOU NEED!!!

I don't want one, but my sister-in-law has one. Says it's awesome. Never a complaint or problem, she says. She, like me, has to drive 12 to 13 miles just going to work everyday, not counting the trip home. Said it has plenty of power.

I actually was asking why ALL hybrids don't have an AC charger for filling the battery at night, even though it might be of minor benefit to the normal hybrids.

When we start our Camry Hybrid, the lights light up and the hybrid system energizes. Because the ICE is cold, it starts up a few seconds later - about the time we back down the driveway and into the street.

The air conditioning is electric but cabin heat is still provided by a heater core. Thus, the need for the ICE to be fully warm. Toyota does something a bit unique and keeps a reservoir of coolant in an insulated thermos-type chamber. I've noticed the engine coolant gets up to temperature a LOT quicker than a standard ICE.

BTW, to maximize the life of the hybrid battery, we only have use of 60% of its capacity. The system never allows it to discharge below 20% and stops charging it when it reaches 80% capacity.

When we start our Camry Hybrid, the lights light up and the hybrid system energizes. Because the ICE is cold, it starts up a few seconds later - about the time we back down the driveway and into the street.

The air conditioning is electric but cabin heat is still provided by a heater core. Thus, the need for the ICE to be fully warm. Toyota does something a bit unique and keeps a reservoir of coolant in an insulated thermos-type chamber. I've noticed the engine coolant gets up to temperature a LOT quicker than a standard ICE.

BTW, to maximize the life of the hybrid battery, we only have use of 60% of its capacity. The system never allows it to discharge below 20% and stops charging it when it reaches 80% capacity.

Volt heats the coolant, so ICE doesnt need to be warm, Chevy engineers, for once thought of almost everything.

I've noticed the engine coolant gets up to temperature a LOT quicker than a standard ICE.

Toyota is rumoured to have jacked up the thermostat level on their cars from the early 2000's in order to meet emissions requirements, which led to a lot of complaints about "oil gelling" which was never that much of an issue before except on cars with turbos.

Toyota might have had an F-1 team, and might be big in engineering on hybrids, but some of the engineering they do is sometimes shady and questionable at best.